The present invention relates to an electronic fuel injection control system for internal combustion engines, and more particularly to such a control system wherein fuel injection is effected at variable intervals in response to a transient in an engine operating condition.
In a prior art electronic fuel injection system, cylinders are simultaneously supplied with fuel at intervals of 720-degree revolution of the engine crankshaft, or each combustion cycle. Fuel injection quantity is derived from intake air quantity and engine speed at 720.degree. intervals to meet power demands under varying operating conditions. When engine acceleration demand occurs immediately after the derivation of the fuel quantity, there occurs a sharp increase in intake air, and therefore air-fuel mixture becomes leaner than is required for acceleration, resulting in an engine having a slow response characteristic to acceleration.
Furthermore, in modern automobiles in which fuel is injected for every two crankshaft revolutions during periods of engine idle, an attempt to inject fuel twice that interval would generate a fuel injection pulse having a duration smaller than the minimum open-time of fuel injectors.